Administrator Guide

APs initially start up with default ack-timeout, cts-timeout and slot-time values. When you modify the
maximum-distance parameter in an rf dot11a radio profile or rf dot11g radio profile, new ack-timeout, cts-
timeout and slot-time values may be derived, but those values are never less then the default values for an
indoor AP.
Mesh radios on outdoor APs have additional constraints, as mesh links may need to span long distances. For
mesh radios on outdoor APs, the effect of the default maximum-distance parameter on the ack-timeout,
cts-timeout and slot-time values depends on whether the APs are configured as mesh portals or mesh
points. This is because mesh portals use a default maximum-distance value of 16,050 meters, and mesh
points use, by default, the maximum possible maximum-distance value.
The maximum-distance value should be set correctly to span the largest link distance in the mesh network so
that when a mesh point gets the configuration from the network it will apply the correct ack-timeout, cts-
timeout and slot-time values.The values derived from the maximum-distance setting depend on the band
and whether 20Mhz/40MHz mode of operation is in use.
The following table indicates values for a range of distances:
Timeouts[usec] --- 5GHz radio --- --- 2.4GHz radio ---
Distance[m] Ack CTS Slot Ack CTS Slot
--------------------------------------------------------------------------
0 (outdoor:16050m) 128 128 63 128 128 63
0 (indoor:600a,6450g) 25 25 9 64 48 9
200 (==default) 25 25 9 64 48 9
500 25 25 9 64 48 9
600 25 25 9 64 48 9
1050 28 28 13 64 48 31
5100 55 55 26 64 55 31
10050 88 88 43 88 88 43
15000 121 121 59 121 121 59
16050 128 128 63 128 128 63
58200(5G limit 20M) 409 409 203 - - -
52650(2.4G limit 20M) - - - 372 372 185
27450(5G limit 40M) 204 204 101 - - -
24750(2.4G limit 40M) - - - 186 186 92
VHT Support on W-AP200 Series, W-AP210 Series, W-AP220 Series, and W-AP270
Series Access Points
This feature enables Very High Throughput (VHT) rates on the 2.4 GHz band, providing 256-QAM modulation
and encoding that allows for 600 Mbit/sec performance over 802.11n networks. Maximum data rates are
increased on the 2.4 GHz band through the addition of VHT Modulation and Coding Scheme (MCS) values 8
and 9, which support the highly efficient modulation rates in 256-QAM. Starting with ArubaOS 6.4.2.0, VHT is
supported on W-AP200 Series, W-AP210 Series, W-AP220 Series, and W-AP270 Series access points on both 20
MHz and 40 MHz channels.
Using the controller’s CLI or WebUI, VHT MCS values 0-9 are enabled, overriding the existing high-throughput
(HT) MCS values 0-7, which have a lower maximum data rate. However, this feature should be disabled if
individual rate selection is required.
Managing 802.11a/802.11g Profiles Using the WebUI
Use the following procedures to define and manage 802.11a and 802.11g RF management profiles Using the
WebUI.
Creating or Editing a Profile
1. Navigate to the Configuration > Wireless > AP Configuration window. Select either the AP Group or
AP Specific tab.
Dell Networking W-Series ArubaOS 6.4.x | User Guide Access Points | 594